It is too expensive to put all my files on the cloud (6TB all up), but it is too difficult to figure out which of my many files need to go on the cloud and which ones need an extra layer of encryption (1 in 50 of them) and which ones I am OK to just leave on local NAS. I need something to sort through the files, strip out duplicates and push the important ones to one of my cloud storage locations. Ideally, it will let me decide which files to encrypt and will interoperate with google drive, onedrive, dropbop and backblaze (b2).

Restoring my ~350 GB backup via zip turned out to take a week to make the zip file available. Which is preposterous. They say you can get a USB hard drive shipped, which is faster, so I did that. Nope, that also takes the exact same amount of time. While I was waiting for the hard drive to ship my zip file finished and was ready to download. It took me 3 more days to download the file.

All told it took 9 days to recover my backup. I've been using this product for years and recommending it to everyone—I feel like a complete idiot. I never noticed that they intentionally avoid revealing how long a restore takes. Even after you start the restore, they don't try to estimate how long it takes because it's so egregious. This company has been around 10 years! I have no idea how the product can be so poor after an entire decade.

And the worst part is the complete indifference and lack of shits their customer support seemed to give. I talked to three or so different people and every single one of them made it abundantly clear that they couldn't possibly care less about how slow their restore feature is, and it was my fault for assuming their product was better than it was and believing their marketing site.

Checkout Arq. It dedups and then backs up your data easily and transparently across the multiple cloud storage services that you mention. It has been the most reliable and easy to use cross client and server service for the couple of years I have been using them. Apart from the services you mention, you can also use Amazon Glacier or Google Nearline, for files that you may not require updating or viewing too often at much cheaper rates.

Duplicati is a free, open-source backup solution that does block-based deduplication. Fully supports end-to-end encrypted backups. Basically, like Arq but free.
The trick is this-- you take your backups to a Google Drive with unlimited storage. You can get that for $10/month by signing up for G Suite for Business. And then you have all your backups in the cloud, in storage you control, fully encrypted, _and_ you have unlimited Google storage for pictures, movies, documents, whatever too.